The present invention relates to a stopper for use with a metallurgical vessel containing molten metal, and specifically to such a stopper of the type wherein a gas, normally an inert gas, is suppled through the stopper for rinsing, flushing or scavenging purposes, as well as for other purposes which would be apparent to one skilled in the art. More particularly, the present invention is directed to such a gas rinsing stopper including a stopper member having therethrough an axial gas passage, a mounting fixture extending into a first end of the gas passage and connected to the stopper for mounting thereof, a gas feed opening at a second end of the gas passage, and a gas supply line extending into the gas passage for supplying rinsing gas thereto and thereby for discharging the rinsing gas through the gas feed opening.
A gas rinsing stopper of this type is disclosed in WO No. 82/03349. However, this known type of gas rinsing stopper is subject to an inherent disadvantage. Thus, when the rinsing gas, for example argon, is supplied to the gas passage and is discharged through the gas feed opening, this creates a reduced pressure at the end of the gas passage to which is mounted the mounting fixture. This causes atmospheric air to be drawn inwardly through this end of the gas passage, and this atmospheric oxygen blends or mixes with the rinsing gas and is discharged therewith through the gas feed opening. This results in a degradation of the quality of the particular metal involved, for example steel, possibly leading to alumina accretions at the nozzle of the metallurgical vessel to be closed by the stopper.